Strong wet bonding hot melt adhesive as well as preparation method and application thereof

Abstract

The invention discloses a strong wet bonding hot melt adhesive as well as a preparation method and application thereof. The strong wet bonding hot melt adhesive comprises the following components in percentage by weight: 10-30% of a main polymer; 40%-60% of tackifying resin; 1%-5% of LDPE (Low-Density Polyethylene)-g- 10%-25% of white mineral oil; 3%-10% of a processing aid; and 0.1%-0.5% of an antioxidant. The preparation method of the strongly wet bonding hot melt adhesive comprises the following steps: mixing all the components, vacuumizing, heating and stirring until the materials are completely molten, stopping stirring, and vacuumizing and defoaming to obtain the strongly wet bonding hot melt adhesive. The strong wet bonding hot melt adhesive is high in peel strength, suitable for non-polar base materials, capable of meeting the production requirement of a high-speed production line, simple in preparation method, low in production cost and suitable for large-scale industrial production and application.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesive technology, specifically to a strong wet-state adhesive hot melt adhesive, its preparation method, and its application. Background Technology

[0002] Hot melt adhesives are commonly used plastic adhesives in hygiene products, labels, and packaging, playing a vital role. Currently, the core of commercially available disposable hygiene products such as adult diapers and baby diapers is generally made of a mixture of fluff pulp and superabsorbent polymer (SAP), wrapped in toilet paper or non-woven fabric. Urine is strongly absorbed through the fluff pulp into the SAP layer, which has excellent absorbency. The SAP in the diaper core absorbs and locks in moisture, while the fluff pulp accelerates the absorption rate and the diffusion rate of liquid within the core layer. The two work together synergistically to give the diaper good dryness.

[0003] However, due to the relatively loose structure of the diaper core, the fluff pulp and SAP cannot be well fixed, leading to clumping and tearing of the core during use. Current solutions address this issue by using hot melt adhesive to bond each layer of the diaper material together, thus fixing the fluff pulp. However, the hot melt adhesives currently used lack sufficient bonding strength, resulting in widespread tearing and clumping even after the diaper core absorbs water, severely impacting the comfort of the diaper. Furthermore, existing hot melt adhesives exhibit weak adhesion when applied to non-polar substrates (e.g., pure cotton), failing to fully meet practical application requirements.

[0004] CN 115838578 A discloses a wet-strength structural adhesive for disposable hygiene products and its preparation method. By using modified petroleum resin and terpene resin as tackifying resins, the obtained wet-strength structural adhesive can stabilize the internal core of disposable hygiene products, thereby giving disposable hygiene products a comfortable user experience and making them less prone to clumping and delamination after absorbing water. However, this wet-strength structural adhesive is not suitable for bonding non-polar substrates.

[0005] Therefore, developing a strong wet-state adhesive hot melt adhesive suitable for non-polar substrates is of great significance. Summary of the Invention

[0006] The purpose of this invention is to provide a strong wet-state adhesive hot melt adhesive, its preparation method, and its application.

[0007] The technical solution adopted in this invention is:

[0008] A strong wet-state adhesive hot melt adhesive comprising the following components by weight percentage:

[0009] Main polymer: 10%–30%;

[0010] Tackifying resin: 40%–60%;

[0011] LDPE-g-MAPEG: 1%–5%;

[0012] White mineral oil: 10%–25%;

[0013] Processing aids: 3%–10%;

[0014] Antioxidant: 0.1%–0.5%.

[0015] Preferably, the main polymer is at least one selected from styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butene-styrene block copolymer (SEBS), and ethylene-vinyl acetate copolymer (EVA).

[0016] Preferably, the tackifying resin is at least one of petroleum resin, hydrogenated C5 petroleum resin, hydrogenated DCPD petroleum resin, hydrogenated C9 resin, rosin resin, and maleic anhydride modified rosin resin.

[0017] Preferably, the LDPE-g-MAPEG (MAPEG-grafted LDPE) is prepared by a method including the following steps: LDPE (low-density polyethylene) and MAPEG (with the structural formula: LDPE-g-MAPEG is obtained by melt grafting of LDPE and initiator.

[0018] Preferably, the weight ratio of LDPE to MAPEG is 100:1 to 5.

[0019] Preferably, the number-average molecular weight of the LDPE is 50,000 g / mol to 500,000 g / mol.

[0020] Preferably, the number-average molecular weight of the MAPEG is 300 g / mol to 2000 g / mol.

[0021] Preferably, the initiator is at least one of dicumyl peroxide (DCP), benzoyl peroxide (BPO), di-tert-butyl peroxide (DTBP), and cumyl hydroperoxide (CHP).

[0022] Preferably, the amount of the initiator is 0.3% to 0.7% of the total weight of LDPE and MAPEG.

[0023] Preferably, the fusion grafting is performed at a temperature of 180°C to 200°C.

[0024] Preferably, the white mineral oil is a naphthenic oil with a weight percentage of cycloalkanes greater than 40%.

[0025] Preferably, the processing aid is at least one of paraffin wax, Fischer-Tropsch wax, PE wax, and PP wax.

[0026] Preferably, the antioxidant is at least one of antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), antioxidant 168 (tris[2,4-di-tert-butylphenyl]phosphite), antioxidant 1076 (octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), antioxidant 1098 (N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine), and antioxidant 1024 (N,N'-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine).

[0027] A method for preparing a strong wet-state adhesive hot melt adhesive as described above includes the following steps: mixing all components, then heating and stirring under vacuum until the material is completely melted, then stopping stirring and degassing under vacuum to obtain the strong wet-state adhesive hot melt adhesive.

[0028] Preferably, the vacuum heating and stirring is carried out at a temperature of 145℃~160℃ and a vacuum degree of -0.10MPa~-0.08MPa.

[0029] A strong wet-state adhesive hot melt adhesive as described above is used for bonding non-polar substrates.

[0030] The beneficial effects of the present invention are: the strong wet adhesive hot melt adhesive of the present invention has high peel strength, is suitable for non-polar substrates, can meet the production requirements of high-speed production lines, and has a simple preparation method and low production cost, making it suitable for large-scale industrial production and application.

[0031] Specifically:

[0032] 1) The strong wet-state adhesive hot melt adhesive of the present invention contains LDPE-g-MAPEG, which effectively improves the hydrophilicity of the hot melt adhesive by grafting hydrophilic side groups on the polyolefin molecular chain and significantly improves the peel strength of the hot melt adhesive, making the hot melt adhesive suitable for non-polar substrates such as pure cotton surface layer, perforated cotton non-woven fabric, imitation cotton non-woven fabric, and fluffy / smooth hot air non-woven fabric;

[0033] 2) The strong wet adhesive hot melt adhesive of the present invention contains LDPE-g-MAPEG, which can effectively adjust the rheological properties of the hot melt adhesive and enhance the wettability of the hot melt adhesive to non-polar substrates, so that the hot melt adhesive can well meet the production requirements of high-speed production lines.

[0034] 3) The preparation method of the strong wet adhesive hot melt adhesive of the present invention is simple, has low production cost, and does not require special production equipment, making it suitable for large-scale industrial production and application. Attached Figure Description

[0035] Figure 1 This is the synthetic route diagram for LDPE-g-MAPEG-1 in Example 1.

[0036] Figure 2 The images are FTIR spectra of LDPE-g-MAPEG-1, LDPE-g-MAPEG-2, and LDPE-g-MAPEG-5 from Examples 1 to 3.

[0037] Figure 3 The images show the FTIR spectra of the strong wet adhesive hot melt adhesive of Example 1 and the hot melt adhesive of Comparative Example 1. Detailed Implementation

[0038] The present invention will be further explained and described below with reference to specific embodiments.

[0039] Example 1:

[0040] A strong wet-state adhesive hot melt adhesive, the composition of which is shown in the table below:

[0041] Table 1. Composition of a strong wet-state adhesive hot melt adhesive

[0042]

[0043]

[0044] Note:

[0045] Preparation method of LDPE-g-MAPEG-1 (synthetic route as follows) Figure 1 As shown below:

[0046] LDPE (LD605 from Beijing Yanshan Petrochemical Co., Ltd., Sinopec Group), MAPEG (MPEG350A from Wuhan Chengtian Fine Chemical Co., Ltd.), and dicumyl peroxide (DCP, Norin) were used. The BC-FF mixture was homogeneous, with a weight ratio of LDPE to MAPEG of 100:1. The weight of dicumyl peroxide was 0.5% of the total weight of LDPE and MAPEG. The mixture was then transferred to a twin-screw extruder for melt grafting at 190°C. The extrusion conditions were: residence time t = 2.5 min, speed r = 100 rpm. The mixture was then pelletized to obtain LDPE-g-MAPEG-1.

[0047] The preparation method of the above-mentioned strong wet-state adhesive hot melt is as follows:

[0048] Mix all components, heat to 155℃ and evacuate to a vacuum degree of -0.08MPa, then stir until the material is completely melted. Stop stirring and evacuate to remove bubbles, to obtain a strong wet-state adhesive hot melt adhesive.

[0049] Example 2:

[0050] A strong wet-state adhesive hot melt adhesive, the composition of which is shown in the table below:

[0051] Table 2. Composition of a strong wet-state adhesive hot melt adhesive

[0052] Components Weight percentage (%) SBS (same as Example 1) 20 Hydrogenated C5 petroleum resin (same as Example 1) 55 LDPE-g-MAPEG-2 1 White mineral oil (same as Example 1) 20 PE wax (same as in Example 1) 3.9 Antioxidant 1010 (same as in Example 1) 0.1

[0053] Note: The preparation method of LDPE-g-MAPEG-2 is the same as that of LDPE-g-MAPEG-1. During preparation, the weight ratio of LDPE and MAPEG is adjusted from "100:1" to "100:2".

[0054] The preparation method of the above-mentioned strong wet-state adhesive hot melt is as follows:

[0055] Mix all components, heat to 155℃ and evacuate to a vacuum degree of -0.08MPa, then stir until the material is completely melted. Stop stirring and evacuate to remove bubbles, to obtain a strong wet-state adhesive hot melt adhesive.

[0056] Example 3:

[0057] A strong wet-state adhesive hot melt adhesive, the composition of which is shown in the table below:

[0058] Table 3. Composition of a strong wet-state adhesive hot melt adhesive

[0059] Components Weight percentage (%) SBS (same as Example 1) 20 Hydrogenated C5 petroleum resin (same as Example 1) 55 LDPE-g-MAPEG-5 1 White mineral oil (same as Example 1) 20 PE wax (same as in Example 1) 3.9 Antioxidant 1010 (same as in Example 1) 0.1

[0060] Note: The preparation method of LDPE-g-MAPEG-5 is the same as that of LDPE-g-MAPEG-1. During preparation, the weight ratio of LDPE and MAPEG is adjusted from "100:1" to "100:5".

[0061] The preparation method of the above-mentioned strong wet-state adhesive hot melt is as follows:

[0062] Mix all components, heat to 155℃ and evacuate to a vacuum degree of -0.08MPa, then stir until the material is completely melted. Stop stirring and evacuate to remove bubbles, to obtain a strong wet-state adhesive hot melt adhesive.

[0063] Comparative Example 1:

[0064] A hot melt adhesive, except that "LDPE-g-MAPEG-1" is replaced by "SBS (same as in Example 1)" by weight, is otherwise identical to the strong wet-state adhesive hot melt adhesive of Example 1, and the preparation process of the hot melt adhesive is also exactly the same as in Example 1. Comparative Example 2:

[0065] A hot melt adhesive is identical to the strong wet-state adhesive hot melt adhesive of Example 1, except that “LDPE-g-MAPEG-1” is replaced by weight of “POE (POE5007 of Wanhua Chemical Group)”. The preparation process of the hot melt adhesive is also identical to that of Example 1.

[0066] Comparative Example 3:

[0067] A hot melt adhesive is identical to the strong wet-state adhesive hot melt adhesive of Example 1, except that “LDPE-g-MAPEG-1” is replaced by “LDPE-g-MAPEG-10” by weight. The preparation process of the hot melt adhesive is also identical to that of Example 1.

[0068] Note: The preparation method of LDPE-g-MAPEG-10 is the same as that of LDPE-g-MAPEG-1. During preparation, the weight ratio of LDPE and MAPEG is adjusted from "100:1" to "100:10".

[0069] Performance testing:

[0070] 1) The Fourier transform infrared (FTIR) spectra of LDPE-g-MAPEG-1, LDPE-g-MAPEG-2, and LDPE-g-MAPEG-5 in Examples 1-3 are shown below. Figure 2 As shown.

[0071] Depend on Figure 2 It can be seen that LDPE-g-MAPEG-1, LDPE-g-MAPEG-2, and LDPE-g-MAPEG-5 are at 1600 cm⁻¹ -1 ~1700cm -1 There is a clear C=O vibration absorption peak within the range, and the intensity of the absorption peak increases with the increase of MAPEG dosage (the PEG content in LDPE-g-MAPEG increases), indicating that MAPEG was successfully grafted onto the LDPE molecular chain.

[0072] 2) The water contact angle test results of LDPE-g-MAPEG-1, LDPE-g-MAPEG-2, and LDPE-g-MAPEG-5 in Examples 1-3 are shown in the table below (LDPE is used as a reference):

[0073] Table 4 Results of water contact angle test

[0074]

[0075] As shown in Table 4, the contact angle of LDPE grafted with MAPEG decreased significantly, from 120.0° to a minimum of 63.3°. The decrease in contact angle increased with the increase in the amount of MAPEG used. The decrease in contact angle reflects the enhanced hydrophilicity of the LDPE-g-MAPEG surface, indicating that the addition of MAPEG effectively improved the hydrophilicity of LDPE.

[0076] 3) The FTIR images of the strong wet-state adhesive hot melt adhesive of Example 1 and the hot melt adhesive of Comparative Example 1 are shown below. Figure 3 As shown.

[0077] Depend on Figure 3 It can be seen that the strong wet-state adhesive hot melt adhesive of Example 1 has a wave number of 1600 cm⁻¹. -1 ~1700cm -1 There is a clear C=O vibration absorption peak in the range, while the hot melt adhesive of Comparative Example 1 does not show a peak at this position, indicating that LDPE-g-MAPEG has been successfully integrated into the hot melt adhesive formulation.

[0078] 4) The strong wet-state adhesive hot melt adhesives of Examples 1-3 and Comparative Examples 1-3 were used on pure cotton fabrics and bamboo fiber fabrics, with an adhesive application amount of 3 gsm. The test results of the dry / wet peel strength of the hot melt adhesives are shown in the table below:

[0079] Table 5. Dry / Wet peel strength test results of hot melt adhesive used on pure cotton fabrics.

[0080] Test sample Dry peel strength (N / inch) Wet peel strength (N / inch) Example 1 1.34 1.02 Example 2 1.32 1.10 Example 3 1.33 1.15 Comparative Example 1 0.96 0.07 Comparative Example 2 0.85 0.06 Comparative Example 3 0.70 0.42

[0081] Table 6. Dry / Wet peel strength test results of hot melt adhesive used in bamboo fiber fabrics

[0082] Test sample Dry peel strength (N / inch) Wet peel strength (N / inch) Example 1 1.73 1.18 Example 2 1.75 1.24 Example 3 1.78 1.36 Comparative Example 1 1.55 0.09 Comparative Example 2 1.30 0.04 Comparative Example 3 1.02 0.54

[0083] Note:

[0084] Dry / wet peel strength: Tested according to "GB / T 2791-1995 Adhesives T Peel Strength Test Method Flexible Materials to Flexible Materials".

[0085] As shown in Tables 5 and 6, the strong wet-state adhesive hot melt adhesives of Examples 1-3, when used on pure cotton and bamboo fiber fabrics, exhibited significantly greater peel strength under both dry and wet conditions than the hot melt adhesives of Comparative Examples 1-3. This indicates that introducing LDPE-g-MAPEG into the hot melt adhesive formulation can significantly increase the polarity and wettability of the hot melt adhesive, thereby significantly improving the adhesion of the hot melt adhesive to non-polar substrates.

[0086] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A strong wet-state adhesive hot melt adhesive, characterized in that, Includes the following components by weight percentage: Main polymer: 10%–30%; Tackifying resin: 40%–60%; LDPE-g-MAPEG: 1%–5%; White mineral oil: 10%–25%; Processing aids: 3%–10%; Antioxidant: 0.1%–0.5%.

2. The strong wet-state adhesive hot melt adhesive according to claim 1, characterized in that: The main polymer is at least one of styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butene-styrene block copolymer, and ethylene-vinyl acetate copolymer.

3. The strong wet-state adhesive hot melt adhesive according to claim 1, characterized in that: The tackifying resin is at least one of petroleum resin, hydrogenated C5 petroleum resin, hydrogenated DCPD petroleum resin, hydrogenated C9 resin, rosin resin, and maleic anhydride modified rosin resin.

4. The strong wet-state adhesive hot melt adhesive according to any one of claims 1 to 3, characterized in that: The LDPE-g-MAPEG is prepared by a method including the following steps: mixing LDPE, MAPEG and an initiator and performing melt grafting to obtain LDPE-g-MAPEG.

5. The strong wet-state adhesive hot melt adhesive according to claim 4, characterized in that: The weight ratio of LDPE to MAPEG is 100:1 to 5.

6. The strong wet-state adhesive hot melt adhesive according to claim 4, characterized in that: The number-average molecular weight of the LDPE is 50,000 g / mol to 500,000 g / mol; the number-average molecular weight of the MAPEG is 300 g / mol to 2,000 g / mol.

7. The strong wet-state adhesive hot melt adhesive according to any one of claims 1 to 3, characterized in that: The white mineral oil is a naphthenic oil with a weight percentage of naphthenes greater than 40%; the processing aid is at least one of paraffin wax, Fischer-Tropsch wax, PE wax, and PP wax; the antioxidant is at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 1098, and antioxidant 1024.

8. A method for preparing a strong wet-state adhesive hot melt adhesive as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Mix all components, then heat and stir under vacuum until the material is completely melted. Stop stirring and degas under vacuum to obtain a strong wet-state adhesive hot melt adhesive.

9. The application of a strong wet-state adhesive hot melt adhesive as described in any one of claims 1 to 8 for bonding non-polar substrates.

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